Analisis Neraca Air Daerah Irigasi Waduk Parangjoho Kabupaten Wonogiri

Abstract

Daerah Irigasi (DI) Waduk Parangjoho atau lebih dikenal sebagai DI Kebonagung berada di wilayah Kecamatan Eromoko, Kabupaten Wonogiri, Jawa Tengah, dengan luas layanan sebesar 522 Ha. Waduk Parangjoho memiliki Daerah Tangkapan Air (DTA) seluas 3214,95 Ha. Perubahan tata guna lahan berupa bertambahnya permukiman dan berkurangnya lahan terbuka di kawasan DTA menyebabkan terganggunya siklus hidrologi dan penyerapan air di tanah, sehingga aliran permukaan pada musim hujan akan meningkat dan pasokan air ke waduk berkurang. Penelitian ini bertujuan mendapatkan nilai neraca air dengan membandingkan nilai ketersediaan air dan kebutuhan air. Ketersediaan air DTA Waduk Parangjoho dihitung menggunakan metode F.J. Mock. Ketersediaan air tertinggi terjadi pada bulan Maret periode I sebesar 1,37 Juta m3 dan terkecil terjadi pada bulan Desember periode II sebesar 0,0002 Juta m3. Sedangkan kebutuhan air Daerah Irigasi Parangjoho terbesar terjadi pada bulan Maret periode II sebesar 0,95 Juta m3 dan yang terkecil pada bulan Februari periode II sebesar 0,01 Juta m3. Secara keseluruhan, neraca air DI Parangjoho mengalami defisit sebesar 2,18 Juta m3. Ketersediaan air DTA Waduk Parangjoho hanya dapat memenuhi 75% dari kebutuhan air Daerah Irigasi Parangjoho.

The irrigation area of the Parangjoho Reservoir, also known as Kebonagung Irrigation Area, is located in Eromoko District, Wonogiri Regency, Central Java, with a service area of 522 hectares. The Parangjoho Reservoir has a Catchment Area (DTA) of 3214,95 hectares. Land use changes in the catchment area, particularly the increase in residential development and the reduction of open land, have disrupted the hydrological cycle and soil water infiltration, leading to increased surface runoff during the rainy season and a reduction in water supply to the reservoir. This study aims to determine the water balance by comparing the water availability and water demand. Water availability in the Parangjoho Reservoir catchment area was calculated using the F.J. Mock method. The highest water availability was recorded in March Period I at 1.37 million m³, while the lowest occurred in December Period II at 0.0002 million m³. Meanwhile, the highest water demand in the Parangjoho Irrigation Area was in March Period II at 0.95 million m³, and the lowest in February Period II at 0.01 million m³. Overall, the water balance in the Parangjoho Irrigation Area indicates a deficit of 2.18 million m³. The available water from the Parangjoho Reservoir catchment area can only meet approximately 75% of the total irrigation water demand.